An SCP or Service Control Point is a standard component of an IN (Intelligent Networks) telephone system which is used to control the service. Standard SCP's in the telecom industry today are deployed using SS7, Sigtran or SIP technologies. The SCP queries the SDP (Service Data Point) which holds the actual database and directory. SCP, using the database from the SDP, identifies the geographical number to which the call is to be routed. This is the same mechanism that is used to route 1-800 numbers. SCP may also communicate with an "intelligent peripheral" (IP) to play voice messages, or prompt for information to the user, such as prepaid long distance using account codes. This is done by implementing feature codes like "#," which can be used to terminate the input for a username or password or can be used for call forwarding. These are realized using Intelligent Network Application Protocol (INAP) that sits above Transaction Capabilities Application Protocol (TCAP) on the SS7 protocol stack. The TCAP is part of the top or 7th layer of the SS7 layer breakdown. SCPs are connected with either SSPs or STPs. This is dependent upon the network architecture that the network service provider wants. The most common implementation uses STPs.
